There is a need for analyte detection that combines the speed and sensitivity of light-based sensors with the high specificity of biomolecular assays such as nucleic acid hybridization assays. In applications ranging from metabolic diagnostics to detection of pathogenic organisms, biomolecules are typically detected through either nucleic acid amplification or antibody recognition. Signaling is usually accomplished by attaching luminescent labels to probes. These conventional tests are typically difficult to multiplex and require equipment that is bulky, intricate and expensive.
Bright et al. describe a microsensor array comprising a sensor located in microwells on the top surface of a light emitter, for example, an LED. See Bright et al, U.S. Pat. No. 6,492,182, filed Jul. 28, 2000, issued Dec. 10, 2002, and U.S. Pat. No. 6,582,966, filed Jun. 24, 2003. Bright et al. disclose a sensor that is physically embedded in sol-gel glass inside the microwells. The sol-gel glass has a surface area of approximately 100 square meters per gram (m2/g) and pores approximately 0.5-500 nanometers (nm) in diameter. The use of microwells complicates manufacture of the detection device. Moreover, the nano-pores in the glass impede or prevent in-diffusion when the analytes are biomolecules such as nucleic acids.